Victron Noob Questions

[TheEngineer]

I'm in the very initial stages of piecing together a 100% off grid energy solution and I'm having a hard time understanding the differences between the many products offered by Victron.

My scenario:

Small house being built on an island with no utilities of any kind. I will NEVER be able to hook up to any sort of grid, so charging batteries from a grid is not an option. I don't plan on buying an expensive automatic generator, so unless my Harbor Freight Predator 9500 gets hooked in, my setup likely won't involve AC from a generator either. I'd like to stick with Victron products at this time.

Does the info above basically rule out the benefit of having a Victron Quattro Inverter/Charger?

Other info:

• I'm looking to store solar in 48V lithium banks, and provide AC power back to the house for both 120V & 240V U.S. appliances.
• Battery Bank - 64 x EVE LF280K 16s4p 48V
• Solar Panels - 24 x Renogy 550w

Should I be looking at the Victron Phoenix Inverter for power back to my panel? Sorry for the noob questions, please don't roast me too much ;-)

 

[sunshine_eggo]

Small house being built on an island with no utilities of any kind. I will NEVER be able to hook up to any sort of grid, so charging batteries from a grid is not an option. I don't plan on buying an expensive automatic generator, so unless my Harbor Freight Predator 9500 gets hooked in, my setup likely won't involve AC from a generator either. I'd like to stick with Victron products at this time.

Why? A generator is a key component to an off grid system. Charging batteries via generator means you get to run your generator at a higher output with more efficient gallon/kWh for a shorter period of time.

Running a generator to only power loads is a great way to gulp fuel at an accelerated rate.

I use my cheap 3850 Predator with my Quattros.

Does the info above basically rule out the benefit of having a Victron Quattro Inverter/Charger?

If you don't plan to charge with generator, you don't need a MP or Quattro.

Other info:

• I'm looking to store solar in 48V lithium banks, and provide AC power back to the house for both 120V & 240V U.S. appliances.
• Battery Bank - 64 x EVE LF280K 16s4p 48V
• Solar Panels - 24 x Renogy 550w

Should I be looking at the Victron Phoenix Inverter for power back to my panel? Sorry for the noob questions, please don't roast me too much ;-)

You should be designing your system and selecting components according to your energy audit requirements.

 

[MisterSandals]

• Battery Bank - 64 x EVE LF280K 16s4p 48V
• Solar Panels - 24 x Renogy 550w

What is your plan to get solar energy harvested into the batteries?

550W x 24 = 13,200W (this is a LOT)

13200W solar / 56V charging voltage = 235A of solar charger(s) (sit down before pricing this/these on Victron site)

235A / (280Ah x 4) = .21C (reasonable)

 

[TheEngineer]

What is your plan to get solar energy harvested into the batteries?

550W x 24 = 13,200W (this is a LOT)

13200W solar / 56V charging voltage = 235A of solar charger(s) (sit down before pricing this/these on Victron site)

235A / (280Ah x 4) = .21C (reasonable)

Please correct me if my math is wrong. I believe I should be able to use the panels in an 8s3p configuration and charge with a single: Victron SmartSolar MPPT RS 450/200-TR - https://www.victronenergy.com/solar-charge-controllers/smartsolar-mppt-rs-450-tr

Am I on the right track here?

​

 

[Q-Dog]

Ability to charge with a generator would be welcome after a week of no sun, so your predator should suffice in such an emergency situation.

If you have no intention of installing a generator you WILL want some redundancy. You should consider splitting the PV panels up between 2 charge controllers so one failure won't eliminate all of your charging.

 

[MisterSandals]

to use the panels in an 8s3p configuration

Can you provide panel specs? Voc and Isc.

My guess is that 3P will be over the 30A limit of MC4 connectors. And 3 parallel strings need to be fused. So you should get a solar combiner box as they make this connectivity easier.

 

[TheEngineer]

Can you provide panel specs? Voc and Isc.

My guess is that 3P will be over the 30A limit of MC4 connectors. And 3 parallel strings need to be fused. So you should get a solar combiner box as they make this connectivity easier.

Here is the spec sheet for the Renogy 550 panels I have:



I've tried using the Victron Website's MPPT Calculator, but it seems to be missing several chargers from the possible results.

 

[MisterSandals]

I've tried using the Victron Website's MPPT Calculator, but it seems to be missing several chargers from the possible results

Which SCCs were you expecting to see as possible solutions?
The 450/200 is too small for that array (235A charging needed)

With an Isc or 14A I wonder if 2P is recommended for MC4cconnectors at 400V+.

What are Victrons recommendations?

 

[TheEngineer]

Which SCCs were you expecting to see as possible solutions?
The 450/200 is too small for that array (235A charging needed)

With an Isc or 14A I wonder if 2P is recommended for MC4cconnectors at 400V+.

What are Victrons recommendations?

Actually, I think I'm catching on more now...

So it looks like my best options are actually 3 solar arrays: 4s2p with each connecting to either a:

SmartSolar MPPT 250/85 or 250/100.

So three arrays each connected to a separate 250/x charger.

Please let me know if I'm way off now or getting closer here.

 

[MisterSandals]

Please let me know if I'm way off now or getting closer here.

Looks good with either of those SCCs for 4S2P.

 

[Bluedog225]

You are way ahead of the game since you have not bought anything yet. Good job.

Sounds like a fun project. Those panels are heavy as heck (I suspect). May not be the best choice for transport.

Where is the island? Generally.

Once you get all, all the details worked out, this group is good at giving specific input on equipment specs and choices.

 

[TheEngineer]

You are way ahead of the game since you have not bought anything yet. Good job.

Sounds like a fun project. Those panels are heavy as heck (I suspect). May not be the best choice for transport.

Where is the island? Generally.

Once you get all, all the details worked out, this group is good at giving specific input on equipment specs and choices.

The island is down in the Exuma Cays of the Bahamas. I have a single acre on a large island without about 6 other homes spread out. I wasn't too worried about the size or weight for transport. All of my supplies are being loaded into two auctioned 48' Reefer trailers (without the refrigeration units). From there they'll be brought over to the island via shallow water barge and dragged up to a spot I've cleared in the bush. This captain charges by trip as opposed to weight/volume. But it's an expensive trip that I only really get one shot at. So there's a couple years worth of planning as to what all will be loaded into those trailers. The electrical side of things is one of my final pieces.

 

[JRH]

Wow, …..wish I was in the islands again… it was a hoot back in the 80’s.

 

[AmpD]

I can verify they are pretty big. Plan on someone helping you move them into place. They did pack and ship well from ‘zon webstore. I lost one set of 2 panels before they arrived. The replacement and second pair arrived with a minor nickel sized ding in a frame if one panel.

All told it took almost 2 months to finally arrive.

Still working on a victron build with them myself. ‘zon you can find pdf links showing you the different watt range, self consumption, terminal sizes ect. Not sure if you found them. It helped me when i finally noticed them in small print 3/4’s down the page.

There is a lot of planning involved and as they said a build layout before buying is a good idea.

One component can limit orhers and a system needs to mesh well for efficiency. I probably should have waited on panels myself but it felt good at the time lol.

 

[WolfbaneAries]

If you're interested, your proposed system is extremely close to my currently installed system:

4.6kw of solar on rooftop going to a single victron mppt 250/100 (4s3p, 160v/30a coming in)
11.5kw on ground mount array going to a victron mppt 450/200 (8s1p x3, 360v/10 x3 coming in, the victron 450/200 has four isolated pv array inputs limited at 20a each so there is no combiner box unlike the 4.6kw array)

These charge two 48v 16s 280ah batteries which supply two victron multiplus ii 48/3000/35 in 240v split phase configuration feeding the main panel.

This is a small off-grid homestead, the 4.6kw system gathers more than enough power for 7-8 months of the year in northern Washington, I recently added the 11.5kw array in hopes of eliminating the wintertime generator usage altogether. We have a solid week of clouds and rain in the forecast so we shall see how it goes... Right now at 10am and totally overcast skies and fog there is 1500w coming in from the pv.

Currently the two batteries are each using a daly 120a bms. I only recently realized that the amperage rating on the daily bms is for output and the charge amperage is half that, which means my batteries can only take 120a of the theoretically available 300a that the system could make available.

As a temporary solution I have reduced the maximum charge on the solar controllers to 120a total which is fine for the moment since the point of such a large system is to be overpaneled to the point of collecting enough power in the winter.

As a permanent solution I have a set of envision 305ah cells that just showed up along with three jk 100a bms which when all put together will be able to accept the full power of the pv system.

I mention all of this to say, pay attention to the charging amperage of the bms that you choose. As mentioned by others you have 235a coming in.

Also I wish I had known that the inputs on the mppt 450/200 were limited to 20a as I originally planned on using a combiner box at the ground mount array and running a single set of wires from there to the mppt. Instead I had to run three sets, which does give me the advantage of being able to track each string of the array separately.

I'd say that you're on the right track with doing three 4s2p arrays each running to a victron 250/100. I believe it best to oversize the controllers and inverters when possible, this will give you 200v/30a into each controller and 56v/78a out.

You could do it with one 450/200 and one 250/100 like I did, but given the prices of those units you're better off with the three 250/100s. I went with the 450/200 because my ground mount array is far from the building and wanted to run the highest voltage I could do as to use smaller gauge wire.

For the record I have been using a Honda 3000iu generator in the winter over the past two years to keep the batteries charged, obviously you will want to wire your inverter up to the generator in case you need it.

 

[pvgirl]

You will want a way to charge batteries, or run your loads off of a generator in case of issues. A transfer switch that allows your loads to be powered by the inverter or the generator would be a good idea, having a generator input for an input on the quadro or multiplus or separate charger also good to have.

Don't forget mounting for the solar panels, you'll want something that can stand up to winds from storms.

 

[ChrisG]

I use my cheap 3850 Predator with my Quattros.

@sunshine_eggo You charge your batteries with a 120v inverter through your 240v split phase Quattros, meaning generator is only connected to one Quattro? If so is that a group setting config?

 

[sunshine_eggo]

@sunshine_eggo You charge your batteries with a 120v inverter through your 240v split phase Quattros, meaning generator is only connected to one Quattro? If so is that a group setting config?

Yes. On that AC input in the Victron System Configurator, "Switch as group" must be disabled.

The generator feeds the L1 inverter allowing passthrough and charge while the L2 inverter inverts.

The Predator is actually split phase, and I will eventually get both legs going, but I almost never use it, and it's not high priority.